Cuttable led strip

ABSTRACT

A light-emitting diode (LED) strip is disclosed. The LED strip includes: an input terminal for receiving a first reference signal, a first LED coupled to an end of a power bus and driven by a first current signal, the first current signal being supplied to the first LED via the power bus; a current-copying circuit arranged to control a flow rate of the first current signal based on the first reference signal; and a first switching element arranged to re-couple the first LED to the power bus when the first LED is disconnected from the end of the power bus as a result of the LED strip being cut at a first location.

FIELD OF INVENTION

The present disclosure relates to light emitting diode (LED) lightsources, in general, and more particularly to a cuttable LED strip.

BACKGROUND

Light-emitting diode (LED) strips can be used in various lightingapplications, including general indoor lighting, decorative lighting,automotive lighting, and landscape lighting. LED strips can often be cutto a size that fits a particular application, and this characteristicmakes them attractive to lighting designers and light fixturemanufacturers. However, some LED strips cannot always be cut withsufficient precision to the size that is needed. For example, flexibleLED strips that feature a segmented design may be cut in lengths thatare multiples of their segment lengths (e.g., 30 cm). While such stripsmay be desirable from a cost perspective, their inability to be cut withgreater precision may limit their utility.

Accordingly, the need exists for a new LED strip that can be cut withgreater precision to a desired length. Furthermore, the need exists fora LED strip system that can be sized with greater precision, whileretaining some of the cost advantages of flexible LED strips thatfeature a segmented design.

SUMMARY

The present disclosure addresses this need. According to aspects of thedisclosure, a light-emitting diode (LED) strip is disclosed. The LEDstrip includes: an input terminal for receiving a first referencesignal, a first LED coupled to an end of a power bus and driven by afirst current signal, the first current signal being supplied to thefirst LED via the power bus; a current-copying circuit arranged tocontrol a flow rate of the first current signal based on the firstreference signal; and a first switching element arranged to re-couplethe first LED to the power bus when the first LED is disconnected fromthe end of the power bus as a result of the LED strip being cut at afirst location.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described below are for illustration purposes only. Thedrawings are not intended to limit the scope of the present disclosure.Like reference characters shown in the figures designate the same partsin the various embodiments.

FIG. 1 is a diagram of an example of a LED strip that features asegmented design, according to aspects of the disclosure;

FIG. 2A is a diagram illustrating the use of the LED strip of FIG. 1inside a light fixture, according to aspects of the disclosure;

FIG. 2B is a diagram illustrating the use of the LED strip of FIG. 1 inconjunction with a cuttable LED strip, according to aspects of thedisclosure;

FIG. 3A is a diagram illustrating the manner in which the LED strip ofFIG. 1 is connected to the cuttable LED strip of FIG. 2B, according toaspects of the disclosure;

FIG. 3B is a diagram illustrating respective connection interfaces ofthe LED strip of FIG. 1 and the cuttable LED strip of FIG. 2B, accordingto aspects of the disclosure;

FIG. 4 is a diagram illustrating an example of a cuttable LED strip,according to aspects of the disclosure;

FIG. 5A is a diagram illustrating another example of a cuttable LEDstrip, according to aspects of the disclosure;

FIG. 5B is a diagram illustrating the operation of the cuttable LEDstrip of FIG. 5A, according to aspects of the disclosure; and

FIG. 6 is a circuit diagram illustrating yet another example of acuttable LED strip, according to aspects of the disclosure.

DETAILED DESCRIPTION

In one aspect, a cuttable LED strip is disclosed that can be cut to sizemore precisely than other LED strip designs. For example, the cuttableLED strip may be cut with a precision that is many times greater thanthe precision with which segmented LED strips can be cut.

In another aspect, the cuttable LED strip may be a LED strip that isprovided alone for use in various applications, such as general indoorlighting, decorative lighting, automotive lighting, and landscapelighting.

In another aspect, the cuttable LED strip may be provided in a kit thatincludes a primary LED strip that is less costly to make but cannot becut with the same precision as the cuttable LED strip. When the cuttableLED strip is provided in such kit, the cuttable LED strip can be used toaugment the primary LED strip as needed. For instance, if the primaryLED strip can be cut to lengths that are multiples of 30 cm and a lengthof 35 cm is needed, a 30-cm segment of the primary LED strip can beaugmented with a 5-cm segment of the cuttable LED strip to achieve thedesired length.

In another aspect, the cuttable LED strip may include a current-copyingcircuit for matching the current driving the cuttable LED strip to thecurrent that is used to drive the primary LED strip. The currentmatching may be necessary to ensure uniform brightness across theprimary LED strip and the cuttable LED strip.

In another aspect, the current-copying circuit may be compatible withboth constant-current and constant-voltage power supplies. This maypermit the cuttable LED strip to be easily deployed in varioussituations.

In another aspect, a light-emitting diode (LED) strip is disclosed,comprising: an input terminal for receiving a first reference signal; afirst LED coupled to an end of a power bus and driven by a first currentsignal, the first current signal being supplied to the first LED via thepower bus; a current-copying circuit arranged to control a flow rate ofthe first current signal based on the first reference signal; and afirst switching element arranged to re-couple the first LED to the powerbus when the first LED is disconnected from the end of the power bus asa result of the LED strip being cut at a first location.

In another aspect, a light-emitting diode (LED) strip is providedcomprising: a power bus; and a plurality of removable sections, whereinany removable section includes: (a) a respective LED that is connectedto an end of the power bus in series with one or more other LEDs thatare located in at least one other removable section, and (b) arespective switching element arranged to recouple the respective LED tothe power bus when the first LED is disconnected from the end of thepower bus as a result of the LED strip being cut in an adjacentlocation.

In another aspect, a system is provided, comprising: a firstlight-emitting diode (LED) strip including a first LED and a second LEDstrip. The second LED strip is arranged to receive a first referencesignal from the first LED strip that is representative of a flow rate ofa first current signal that drives the first LED. The second LED stripincludes: a power bus; a plurality of second LEDs connected in series toan end of the power bus and driven by a second current signal; and acurrent-copying circuit arranged to match a flow rate of the secondcurrent signal to that of the first current signal based on the firstreference signal.

FIG. 1 is a diagram of an example of a LED strip 100, according toaspects of the disclosure. The LED strip 100 is a flexible LED stripsuitable for use in linear light fixtures. The LED strip includessegments 110 that can be connected in parallel to either a constantcurrent or constant voltage LED power supply. Each of the segments 110may have a fixed length (e.g., 30 cm) and include a series of LEDs 120.The LED strip 100 may be rolled on a reel 130 and it may include anadhesive backing that is exposed when a release liner 140 is peeledaway.

In the present example, the LED strip 100 is manufactured into a seriesof repetitive segments 110 that have fixed lengths. Despite itsflexibility, the length of the LED strip can only increase or decreaseper unit segment. In order to achieve a practical trade-off between thetotal driving current and the voltage, the LEDs in each segment areconnected in series. Consequently, when the LED strip is cut to length,it has to be cut by the complete segment. In other words, the flex strip100, unless custom designed for a fixture, would not necessarily matchthe length of every fixture that it will be attached to, either leavinga piece of one of its segments, that cannot fit, hanging outside of thelight fixture or creating a dark zone in the light fixture. Whiledesigning a flex strip for every new fixture solves this issue, itcreates the problem of an overblown inventory of different LED stripmodels.

FIG. 2A depicts an example of a light fixture 210 having a portion ofthe LED strip 100 installed therein. As illustrated, the length of thelight fixture 210 is greater than the combined length of the twosegments 110 that are placed inside it, but less than three times thesegments' length. Thus, when two of the segments 110 are installed inthe light fixture 210, some of the space available in the light fixtureremains unfilled, which may lead to the appearance of a dark spot whenthe light fixture 210 is turned on.

FIG. 2B is a diagram illustrating the use of a cuttable LED strip 220 tooccupy the unfilled space in the light fixture 210. In the presentexample, the cuttable LED strip 220 is cut to the length of the infilledspace and connected to the segments 110 to form a continuous lightsource that spans the entire length of the light fixture 210.

FIG. 3A depicts an example of a system 300 including at least onesegment 110 of the LED strip 100 along with the cuttable LED strip 220.As illustrated, after the cuttable LED strip 100 is cut to the desiredsize, it can be connected to the LED strip 100 via a connector 310.Connector 310 may be any suitable type of connector that is arranged tocouple the terminals on the end of the segment 110 to those of thecuttable LED strip 220. For example, connector 310 may include aslide-in wire connector, a strip-to-strip connector, a gaplessconnector, and/or any other suitable type of connector.

FIG. 3B depicts an example of a connection terminal configuration of theLED strip 100 and the cuttable LED strip 220. As illustrated, eachsegment 110 of the LED strip 100 may be provided with a set of threeterminals, including a power terminal 322, a ground terminal 326, and areference terminal 324. Similarly, the cuttable LED strip 220 mayinclude a power terminal 332, a ground terminal 336, and a referenceterminal 334. When the connector 310 is used to connect the segment 110of the LED strip 100 to the cuttable LED strip 220, power terminal 322is coupled to power terminal 332, power terminal 322 is coupled to powerterminal 332, ground terminal 326 is coupled to ground terminal 336, andreference terminal 324 is coupled to reference terminal 334.

According to aspects of the disclosure, the power terminals 322 and 332may be used to connect the cuttable LED strip 220 to the power supply ofthe LED strip 100. Similarly, the ground terminals 326 and 336 may beused to connect the cuttable LED strip 220 to ground. Furthermore, thereference terminals 324 and 334 may be used to feed a reference signalfrom the LED strip segment 110 to the cuttable LED strip 220. Thereference signal may be any suitable type of signal that isrepresentative of the flow rate of current through the LEDs in thesegment 110. As is further discussed below, the reference signal is usedto match the current in the cuttable LED strip to the current in the LEDsegment 110 in order to ensure uniform brightness.

Although in the present example the LED strip 100 includes only onesegment 110, alternative implementations are possible in which the LEDstrip 100 includes a series of segments 110. Additionally oralternatively, when the LED strip 100 includes a series of segmentsconnected in parallel to a power supply, the reference signal may berepresentative of the flow rate of current that is used to drive theLEDs in only one of the segments (e.g., the last segment). Additionallyor alternatively, in some implementations, the reference signal may berepresentative of the flow rate of current that is used to drive onlysome of the LEDs in a particular segment (e.g., the last segment).

Although in the present example the LED strip segment 110 and thecuttable LED strip 220 have identical connection interfaces, in someimplementations their connection interfaces may differ. For example, theconnection interfaces may have different numbers of terminals or one ofthe connection interfaces may be missing a terminal. As another example,the terminals in the connection interface of the LED strip segment 110may have different size(s), shape(s), or location(s) than those of thecuttable LED strip 220. When the connection interfaces differ, theconnector 310 may play the secondary role of an adapter between the twointerfaces. Thus, the present disclosure is not limited to any specifictype of connection interface on either the LED strip segment 110 or thecuttable LED strip 220.

FIG. 4 is a diagram of an example a cuttable LED strip 400, according toaspects of the disclosure. The cuttable LED strip 400 includes a powersupply section 410, a series of removable sections 420, and a series ofseparation areas 430. The separation areas 430 are interleaved with theremovable sections 420, as shown.

The power supply section 410 may include an input interface 412 and acurrent-copying circuit 414. The input interface 412 may include one ormore connection terminals, such as the terminals 332, 334, and 336,discussed with respect to FIG. 3B. Additionally or alternatively, theinput interface 412 may include one or more electronic components and/orcircuitry for conditioning or modifying any of the signals that arereceived via the input interface 412.

The signals received via the input interface 412 may include a referencesignal and a power signal. Both the power signal and the referencesignal may be received from an external LED strip that is connected tothe cuttable LED strip 400. According to the present example, thereference signal may be representative of the flow rate of current thatdrives one or more LEDs in the external LED strip. The power signal maybe received from a power supply of the external LED. The power supplymay be either separate or integrated into the LED. The external LEDstrip and the cuttable LED strip may be connected in parallel to thepower supply.

The power signal may be used to drive one or more of the LEDs 422 thatare part of the cuttable LED strip 400. The current-copying circuit mayinclude any suitable type of circuitry that is configured to match theflow rate of the power signal to that of the signal used to drive theone or more LEDs in the external LED strip. In other words, thecurrent-copying circuit may copy the current in the external LED stripto the cuttable LED strip to ensure uniform brightness of the externalLED strip and the cuttable LED strip.

Each removable section 420 may be removed from the cuttable LED stripwithout affecting the functionality of those removable sections 420 thatremain coupled to the power supply section 410. Each removable section420 may include a respective LED 422, a respective reserve track 424,and a respective switching element 426. The respective LED 422 of any ofthe removable sections 420 may include one or more LEDs that areinstalled in that section. The respective reserve track 424 of any ofthe removable sections 420 may provide an alternative current path toany of the LEDs 422 that remain after the cuttable LED strip 400 is cutin two pieces. The respective switching element 426 of any of theremovable sections 420 may be configured to close the respective reservetrack of that removable section when the separation area immediatelyupstream from the removable section is cut.

As the name suggests, the separation areas 430 are locations in the LEDstrip 400 where the cuttable LED strip 400 can be safely cut in order toreduce its length. When the cuttable LED strip 400 is cut in two piecesin any of the separation areas 430, the functionality of the LEDs in theremovable sections located downstream from that separation area isretained. In some implementations, each of the separation areas 430 maybe marked in order to inform users that the cuttable LED strip 400 canbe cut there. Additionally or alternatively, in some implementations,each of the separation areas 430 may be perforated and/or precut inorder to make it easier for users to pull different portions of thecuttable LED strip 400 apart. An example of one possible separation areaimplementation is discussed further below with respect to FIGS. 5A-B.

FIG. 5A is a diagram of an example of a cuttable LED strip 500,according to aspects to the disclosure. The cuttable LED strip 500includes a power supply section 510, a plurality of removable sections520, and a plurality of separation areas 530. The power supply section510 may be the same or similar to the power supply section 410 discussedwith respect to FIG. 4. Each of the removable sections 520 may include arespective LED, a respective reserve track, and a respective switchingelement. Each of the separation areas 530 may include a respectivetrip-wire, as shown.

As illustrated, the LEDs in different removable sections 520 areconnected in series to the end of a power bus. The respective reservetracks of the removable sections 420 are connected in parallel to thepower bus. The reserve tracks are spaced apart from one another, andeach reserve track is provided with a respective switching element thatis arranged to open and close that reserve track. In someimplementations, each respective switching element is provided with twoconnect-terminals and a control terminal C_(T), and configured to openand close a path between the two connect-terminals depending on thesignal that is applied to the control terminal (e.g., a voltage signal).The respective control terminal C_(T) of each switching element isconnected to the power bus via a respective trip-wire. When the powerbus is intact, the voltage of the power bus is applied to the controlterminals C_(T) of the switching elements, and the switching elementsremain in the open state.

Referring to FIG. 5B, when the cuttable LED strip is cut into aremaining portion and a removed portion in separation area 530 x, theLED in the removable section 520 x is disconnected from the end of thepower bus. However, the trip-wire in separation area 530 x is alsosevered as a result of cuttable LED strip 500 being cut, and this makesit impossible for the voltage of the power bus to continue to be appliedto the control terminal C_(T) of the switching element in the removablesection 520 x. The absence (or the mere drop) of voltage at the controlterminal C_(T) of the switching element of the removable section 530 xcauses the switching element to close when the cuttable LED strip 500 isenergized. This in turn causes the LED in removable section 520 x to bere-connected to the power bus, along with one or more other LEDs thatare located downstream from it.

FIG. 6 is a circuit diagram of a system including a cuttable LED strip600 connected to a LED strip 650. The LED strip 650 includes a powersupply S1 and a plurality of LEDs connected in series with a resistorRs. The power supply S1 may be either an external power supply or abuilt-in power supply. Furthermore, the power supply S1 may be aconstant current power supply or a constant voltage power supply.Although in the present example, the LED strip 650 includes one segment,alternative implementations are possible in which the LED strip 650includes multiple segments connected in parallel to the power supply S1,such that when the LED strip 650 is turned on, the same current flowsthrough each of the segments.

The cuttable LED strip 600 is connected to the LED strip 650 via theterminals labeled PWR, REF, and GND, respectively, and is powered by thepower supply S1 of the LED strip 650. The cuttable LED strip 600includes a power supply section 610, a plurality of removable sections620, and a plurality of separation areas 630, as shown. The separationareas 630 and the removable sections 620 are interleaved.

The power supply section 610 includes a current-copying circuit that isconfigured to copy the current used to drive the LEDS in the LED strip650 to the cuttable LED strip 600. As illustrated, the LEDs in the LEDstrip 650 are driven with the first current signal I₁, and the LEDs inthe cuttable LED 600 are driven with the second current signal I₂. Thus,in some implementations, the current-copying circuit may include anysuitable type of circuitry that is configured to cause the flow rate ofthe second current signal I₂ to match the flow rate of the first currentsignal I₁. In some implementations, the flow rate of the second currentsignal I₂ may be considered to match the flow rate of the first currentsignal I₁ when the flow rate of the second current signal I₂ is equal tothe flow rate of the first current signal I₁ Additionally oralternatively, in some implementations, the flow rate of the secondcurrent signal I₂ may be considered to match the flow rate of the firstcurrent signal I₁ when the flow rate of the second current signal I₂ iswithin a predetermined distance of the flow rate of the first currentsignal I₁. Thus, in some implementations, the current-copying circuitmay cause the LEDs in the cuttable LED strip 600 to receive the same (orsimilar) current as the LEDs in the LED strip 650, thereby ensuringuniform brightness of the system.

Additionally or alternatively, in some implementations, thecurrent-copying circuit may purposefully cause the LEDs in the cuttableLED strip 600 to receive a current that is offset from the current I₁ bysome distance in order to compensate for differences between the LEDs inthe LED strip 650 and the cuttable LED strip 600. For example, in suchimplementations, the current-copying circuit may ensure that the flowrate of the current signal I₂ is either lower or higher by apredetermined amount than the flow rate of the current I₁.

More particularly, in the example of FIG. 6, the current-copying circuitincludes an operational transconductance amplifier (OTA) U1 that isarranged to feed its output to a metal-oxide-semiconductor field-effecttransistor (MOSFET) Q1. The operational amplifier U1 receives a firstreference signal and a second reference signal at its inputs. The firstreference signal is generated using resistor Rs and it indicates theflow rate of the current signal I₁. The second reference signal isgenerated using resistor Rs1 and it indicates the flow rate of currentsignal I₂ across the LEDs in the cuttable LED strip 600. Both the firstreference signal and the second reference signal may be voltage signals,with the first reference signal being the voltage drop across resistorRs and the second reference signal being the voltage drop acrossresistor Rs1. In some implementations, the operational amplifier U1 mayuse the difference between the first reference signal and the secondreference signal to cause the flow rate of the current signal I₂ tomatch the flow rate of the current signal I₁.

In some implementations, resistors Rs and Rs1 may have the sameresistance. In some implementations, the power supply section 610 mayinclude one or more LEDs. In some implementations, the power MOSFET Q1may be selected to have a sufficient power rating to accommodate thevoltage drop when all of the removable sections 620 have been removed.In some implementations, the OTA U1 may be powered using a voltageregulator U2. Voltage regulator U2 may be a traditional TL431-basedvoltage regulator and/or any other suitable type of voltage regulator.Alternatively, in some implementations, a Zener diode can be usedinstead of the voltage regulator U2 to save on cost.

Each of the removable sections 620 may include a respective LED L1, arespective reserve track N3-N4, a respective p-channelmetal-oxide-semiconductor field-effect transistor (PMOS) Q2, arespective resistor R1, and a respective resistor R2. In any particularremovable section 620, the function of the PMOS Q2 and resistors R1 andR2 is to connect the anode of the LED L1 to the power bus N1-N2 when aportion of it is cut away. In any particular removable section 620, thegate of the PMOS Q2 is normally shorted to its source by a conductor 640(e.g., a trip-wire) situated in the separation area 630 that is locatedimmediately upstream from that removable section. This causes the PMOSQ2 to be turned off, thus maintaining its respective reserve track N3-N4open.

When the cuttable LED strip 500 is cut in two pieces in a particularseparation area 630, the respective conductor 640 of that separationarea is severed. As a consequence, several changes occur in theremovable area 620 that is located immediately downstream from theparticular separation area 630. For ease of description, this separationarea is referred to as “corresponding removable area.” Moreparticularly, the two resistors R1 and R2 of the corresponding removablearea form a resistive divider for biasing the gate of the PMOS Q2. Thisturns on the PMOS Q2 of the corresponding separation area and closes itsreserve track N3-N4. When the PMOS Q2 of the corresponding removablearea is turned on, it connects the anode of the LED that is connected toits drain to the power bus N1-N2, thus closing the circuitautomatically.

In some aspects, the design of cuttable LED strip 600 can accommodateboth constant-voltage power supplies (e.g., power supplies that providea given output voltage, constant within a range of possible outputcurrents) and constant-current power supplies (e.g., power supplies thatprovide a given output current, constant within a range of possibleoutput voltages). In some implementations, as the length of the cuttableLED strip 600 increases, constant voltage drivers may ensure constantvoltage but increasing current. Additionally or alternatively, in someimplementations, the resistive divider formed by resistors R1 and R2 maybe necessary in order to limit the gate-source voltage of PMOS Q2 asmost commercially available PMOS have a max |Vgs| of 20V while thecommon bus voltage for LED strips is in the range from 24 to 48V.

FIGS. 1-6 are provided as an example only. At least some of the elementsdiscussed with respect to these figures can be arranged in differentorder, combined, and/or altogether omitted. It will be understood thatthe provision of the examples described herein, as well as clausesphrased as “such as,” “e.g.”, “including”, “in some aspects,” “in someimplementations,” and the like should not be interpreted as limiting thedisclosed subject matter to the specific examples. As used throughoutthe present specification, the term “cut” can refer to any actionresulting in the division of a LED strip into two portions (e.g., aremaining portion and a removed portion). As used throughout the presentspecification, the term cut does not presuppose or exclude the use of aknife, scissors or some other instrument. As used throughout the presentspecification, the term “cut” encompasses actions such as tearing apart,pulling apart, breaking apart, etc.

Having described the invention in detail, those skilled in the art willappreciate that, given the present disclosure, modifications may be madeto the invention without departing from the spirit of the inventiveconcepts described herein. Therefore, it is not intended that the scopeof the invention be limited to the specific embodiments illustrated anddescribed.

1. A light-emitting diode (LED) strip, comprising: an input terminal forreceiving a first reference signal; a first LED coupled to an end of apower bus and driven by a first current signal, the first current signalbeing supplied to the first LED via the power bus; a current-copyingcircuit arranged to control a flow rate of the first current signalbased on the first reference signal; a first switching element arrangedto re-couple the first LED to the power bus when the first LED isdisconnected from the end of the power bus as a result of the LED stripbeing cut at a first location; a second switching element arranged tore-couple the second LED to the power bus when the second LED isdisconnected from the end of the power bus as a result of the LED stripbeing cut at a second location; a first conductor that couples a firstcontrol terminal of the first switching element to the power bus, thefirst conductor being disposed at the first location; and a secondconductor that couples a second control terminal of the second switchingelement to the power bus, the second conductor being disposed at thesecond location and such that the first switching element is arranged totransition to a closed state when the first conductor is severed as aresult of the LED strip being cut at the first location, and, the secondswitching element is arranged to transition to a closed state when thesecond conductor is severed as a result of the LED strip being cut atthe second location.
 2. The LED strip of claim 1, wherein: the firstreference signal is representative of a flow rate of a second currentsignal that drives one or more external LEDs; and the current-copyingcircuit is arranged to match the flow rate of the first current signalto that of the second current signal.
 3. The LED strip of claim 1,further comprising a conductor coupling a control terminal of the firstswitching element to the power bus, wherein the first switching elementis arranged to transition to a closed state when the conductor issevered as a result of the LED strip being cut at the first location. 4.The LED strip of claim 1, further comprising: a second LED locatedupstream from the first LED, the second LED being coupled in series withthe first LED to the end of the power bus.
 5. (canceled)
 6. The LEDstrip of claim 4, wherein: when the LED strip is cut in the firstlocation, the second LED is removed from the LED strip and the first LEDremains in the LED strip, and when the LED strip is cut in the secondlocation, both the first LED and the second LED remain in the LED strip.7. The LED strip of claim 1, wherein: the first reference signal is avoltage signal, and the current-copying circuit includes an operationalamplifier arranged to control the flow rate of the first current signalbased on a difference between the first reference signal and a secondreference signal that is representative of a voltage drop developed atleast in part by the first LED.
 8. The LED strip of claim 7, wherein thecurrent-copying circuit further includes a resistor coupled in serieswith the first LED, and the second reference signal is generated usingthe resistor.
 9. The LED strip of claim 7, wherein the current-copyingcircuit further includes a voltage regulator that is arranged to powerthe operational amplifier. 10-20. (canceled)
 21. A light-emitting diode(LED) strip, comprising: an input terminal for receiving a firstreference signal; a first LED coupled to an end of a power bus anddriven by a first current signal, the first current signal beingsupplied to the first LED via the power bus; a current-copying circuitarranged to control a flow rate of the first current signal based on thefirst reference signal; a first switching element arranged to re-couplethe first LED to the power bus when the first LED is disconnected fromthe end of the power bus as a result of the LED strip being cut at afirst location; a second LED located upstream from the first LED, thesecond LED being coupled in series with the first LED to the end of thepower bus such that when the LED strip is cut in the first location, thesecond LED is removed from the LED strip and the first LED remains inthe LED strip, and, when the LED strip is cut in the second location,both the first LED and the second LED remain in the LED strip.
 22. TheLED strip of claim 21, wherein: the first reference signal isrepresentative of a flow rate of a second current signal that drives oneor more external LEDs; and the current-copying circuit is arranged tomatch the flow rate of the first current signal to that of the secondcurrent signal.
 23. The LED strip of claim 21, further comprising aconductor coupling a control terminal of the first switching element tothe power bus, wherein the first switching element is arranged totransition to a closed state when the conductor is severed as a resultof the LED strip being cut at the first location.
 24. The LED strip ofclaim 21, further comprising a second switching element arranged tore-couple the second LED to the power bus when the second LED isdisconnected from the end of the power bus as a result of the LED stripbeing cut at a second location.
 25. The LED strip of claim 24, furthercomprising: a first conductor that couples a first control terminal ofthe first switching element to the power bus, the first conductor beingdisposed at the first location; and a second conductor that couples asecond control terminal of the second switching element to the powerbus, the second conductor being disposed at the second location, whereinthe first switching element is arranged to transition to a closed statewhen the first conductor is severed as a result of the LED strip beingcut at the first location, and wherein the second switching element isarranged to transition to a closed state when the second conductor issevered as a result of the LED strip being cut at the second location.26. The LED strip of claim 21, wherein: the first reference signal is avoltage signal, and the current-copying circuit includes an operationalamplifier arranged to control the flow rate of the first current signalbased on a difference between the first reference signal and a secondreference signal that is representative of a voltage drop developed atleast in part by the first LED.
 27. The LED strip of claim 26, whereinthe current-copying circuit further includes a resistor coupled inseries with the first LED, and the second reference signal is generatedusing the resistor.
 28. The LED strip of claim 26, wherein thecurrent-copying circuit further includes a voltage regulator that isarranged to power the operational amplifier.